Homogenization is the breaking down and mixing of the components of an emulsion or dispersion. A major use of homogenizers is to break down and disperse milk fat into the bulk of skim milk. This delays creaming of milk fat globules. Homogenizers are also used to process other emulsions such as silicon oil and to process dispersions such as pigments, antacids and various paper coatings.
In the most widely used type of homogenizer, the emulsion is introduced at high pressure of from 500 psi to 10,000 psi to a central bore within an annular valve seat. The emulsion is forced out through a narrow gap between the valve seat and a valve member. Through the gap, the emulsion undergoes extremely rapid acceleration as well as an extreme drop in pressure. This violent action through the valve breaks down globules within the emulsion to produce the homogenized product.
The degree of homogenization is a function of the difference between the pressure of the emulsion at the inlet of the valve and the pressure at the outlet. In the past, homogenizers have not typically been required to operate at pressures of greater than 10,000 psi. However, recent applications such as cell disruption have required significantly higher pressures of about 15,000 psi or more.
A typical homogenizer system includes a homogenizer valve mounted to the side of a pump block. The pump is a plunger pump having multiple plungers which draw fluid from a common suction manifold and discharge it into a common discharge manifold delivering high pressure fluid to the homogenizer valve. The suction and discharge manifolds are cross bores which extend parallel to opposite faces of the block. Valve bores drilled through one of those faces join the two manifolds, and a valve assembly is positioned at each end of each of those valve bores. Another set of bores is drilled through an adjacent face of the block to form pump chambers which house the plungers. Each pump chamber intersects each valve bore at a 90 degrees angle. Each plunger reciprocates in a pump chamber to draw fluid through a suction valve from the suction manifold and force the fluid through the discharge valve into the discharge manifold which is connected to the homogenizer valve. As such, the homogenizer has a primary fluid flow path extending from the suction manifold and through the suction valves, the pump chambers, the discharge manifold and the homogenizer valve.
For a constant flow rate pump, a desired homogenizing pressure is maintained by adjusting the gap between the valve member and the valve seat. In conventional systems, that adjustment is made by an actuator assembly which may be a spring-loaded handwheel or a hydraulic or pneumatic actuator system. The hydraulic or pneumatic system provides for regulating of the process via a control panel, eliminating the need for manual adjustments.